Hi, I recently visited a nurse practitioner to have a routine pap as well as std testing done. My IGG came back negative for HSV1 and HSV2 but she said my IGm came back positive. I have read that IGm testing is outdated and can produce false positive results due to the chemistry of the test itself. The nurse practitioner said that the IGm came back positive for HSV2 but I thought IGm's were not type specific? Please help. Thanks!
Hello, Thank you for your question,
Your age ?
are you sexually active ?
but not for the last month
Well both HSV 1 and HSV 2 have type specific antibodies that can be detected.
IgM means that there is acute infection
but I have read that only the IGG test can be truly accurate
that is less than 4 weeks old.
while IgG means a chronic infection or previous exposure to this virus.
but is it possible for igm to have a false positive result?
i have read this in many forums
I am always very safe
and don't understand how it could be possible
These are pretty sensitive tests, false positive is less likely and can occur with other infections
of herpes virus.
but IGm is type specific? i have read that it is not
It is true that IgM of HSV1 can give false positive for HSV2
and that I should be retested in 12-16 weeks and only focus on my IGG
so it's possible i have HSV1
because their main structure is the same.
and not HSV2
that is something I have read
Yes it is possible as these antibodies can give false results with one another.
I have never had a symptom (I realize some people never show signs ever)
I am just very worried and stressed
So this may be the case.
but I read that 80% of adults have HSV1
Yes it is true
more than 70% of population has it.
so it is very possible that HSV1 was mixed up with HSV2?
even if I've had signs of neither?
so it is nothing to worry, ideal is to get it rechecked.
Because if this was true positive then your IgG antibodies should be positive after
I had my test 4 weeks after the previous sexual encounter
HSV1 can be present in the body even without symptoms.
both IGG's came back negative
she said the igm was high
does this make a difference?
then there are high chances that it is false positive. IgM represent an acute infection that is less than 6 months old
so the IgM would be accurate within 2 weeks of a sexual encounter?
and not thereafter?
and high titers means that less chance of false result, although it is not the criterion but less chances of being false if titers are high. So i would repeat this test after 4 weeks and see if it is still positive.
IgM are acute while IgG appear after 4 weeks and can be delayed upto 6 months.
SO best option is to repeat this test.
You have more questions ?
why does the CDC regulations say to not use iGm testing?
Because of high false results.
they ask doctors not to use it
so can I disregard until my next IGG exam?
it's putting a lot of stress on me
and I don't want to rely and worry about something that shouldn't be administered by doctors
this test also comes positive with other types of viruses and some bacterial infections so CDC tell not to use it
IGG's were both normal and IgM was high and that was all my nurse practitioner seemed to focus on
she never told me that since IGG was negative that I should be retested in 4 weeks
If IgG does not comes positive this also means that it was false positive.
So best is to repeat it.
Your questions ?
I think that's it. So I can stop worrying until the next test?
Wishing you best of luck.
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MBBS/FCPS(Internal medicine/cardiology) MRCP(R) U.K